The invention is based on a pressure regulating valve for a storage-type fuel injection system for internal combustion engines.
A pressure regulating valve of this kind is known from the literature, such as the textbook Dieselmotor-Management [Diesel Engine Management], second edition, Verlag Vieweg, 1998, pages 270, 271. This pressure regulating valve is used to regulate the pressure in a fuel reservoir. The pressure regulating valve has a pistonlike valve member, guided axially displaceably in a bore counter to the force of a closing spring. The valve member acts in the closing direction on a closing element of the pressure regulating valve and presses the valve against a valve seat. The valve member forms an armature of an electromagnet, which can be supplied with current to reinforce the force of the closing spring. By means of the closing spring, via the valve member, the closing element is pressed with a certain force against the valve seat, and as a result of the pressure acting on the closing element, the closing element is lifted from the valve seat in the fuel reservoir when the force generated by the pressure exceeds the force of the closing spring, and fuel flows out of the fuel reservoir via the open pressure regulating valve into a relief chamber. To establish a higher pressure in the fuel reservoir, current is supplied to the electromagnet, so that the closing force exerted on the closing element via the valve member is increased, and thus it is not until there is a higher pressure in the fuel reservoir that the closing element lifts from the valve seat and causes fuel to flow out of the fuel reservoir into the relief chamber. The valve member has a relatively great length and is cylindrical, and because of dimensional and positional tolerances of the valve member and the bore it is difficult to achieve a defined guidance and contact of the valve member in the bore over its entire length. An undefined contact of the valve member in the bore, a skewed position of the valve member above all with electromagnets that are supplied with current, and as a result increased friction between the valve member and the bore can thus all occur. This in turn can lead to a functional impairment of the pressure regulating valve, and in particular fast movements of the valve member are impaired, thus precluding exact establishment of the pressure in the fuel reservoir.
The pressure regulating valve according to the invention has an advantage over the prior art that the valve member is guided in a defined way in the bore via its guide portions, and the functional reliability of the pressure regulating valve is thus improved.
Advantageous features and refinements of the pressure regulating valve of the invention are disclosed hereinafter. Canting of the valve member in the bore is averted by an embodiment of the invention.
The invention will be better understood and further objects and advantages thereof will become more apparent from the ensuing detailed description of a preferred embodiment taken in conjunction with the drawing.